Novel ecology and risks of the plastisphere as a newly expanding microbial habitat

Plastic offers a new niche for microorganisms, the plastisphere. The ever-increasing emission of plastic waste makes it urgent to understand the microbial ecology of the plastisphere and associated impacts. Here we present a global fingerprint of the plastisphere, analyzing samples collected from freshwater, seawater, and terrestrial ecosystems. The plastisphere assembles a distinct microbial community that has a clearly higher heterogeneity and a more deterministically-dominated assembly compared to natural habitats. New coexistence patterns - loose and fragile networks with mostly specialist linkages among microorganisms that are rarely seen in natural habitats - are seen in the plastisphere. Plastisphere microbiomes generally have high potential to metabolize organic compounds, which could accelerate carbon turnover. Microorganisms involved in the nitrogen cycle are also altered in the plastisphere, especially in freshwater plastispheres, where a high abundance of denitrifiers could increase the release of nitrite (aquatic toxicant) and nitrous oxide (greenhouse gas). Enrichment of unique animal, plant, and human pathogens means that the plastisphere could become an increasingly mobile reservoir of harmful microorganisms in the future. Our findings highlight that if the trajectory of plastic emission is not reversed, the expanding plastisphere could pose critical planetary health challenges.